Antimicrobial activity of Agarwood oil against multiple-drug-resistant (MDR) microbes of clinical, food and environmental origin

Abstract

Background and Objectives: Multiple-Drug-Resistance (MDR) among bacteria is an imminent problem and alternative therapies are seen as a future abode. Agarwood Oil (AO) is described to possess antimicrobial activity besides many other medicinal utilities. This paper discusses the antimicrobial activity of AO on MDR and non-MDR strains of microbes of 69 genera isolated from clinical and non-clinical samples.

Methods and Results: In this study sensitivity of microbes was determined for conventional antimicrobials and AO using disc diffusion assay followed by determination of minimum inhibitory concentration (MIC) using agar well dilution assay. A total of 18.5% (522) strains were found sensitive to AO. Carbapenem resistant bacterial strains were more often (p, ≤0.01) resistant to antibiotics with 4.2 times more odds (99% CI, 2.99-5.90) of being MDR than carbapenem sensitive strains but no difference in their AO sensitivity was observed. However, MDR strains were more often (p, <0.001) resistant to AO than non-MDR strains. Bacteria isolated from dogs were more often sensitive to AO than those from buffaloes, human, horse, and cattle. On the other hand, bacteria from pigs were more often (p, ≤0.05) resistant to AO than bacteria from human, cattle, buffaloes, dogs, wild carnivores and birds. Oxidase positive Gram positive bacteria had 4.29 (95% CI, 2.94-6.27) times more odds to be AO sensitive than oxidase negative Gram negative bacteria. Bacillus species strains were the most sensitive bacteria to AO followed by strains of Streptococcus and Staphylococcus. The MIC of AO for different bacteria ranged from 0.01 mg/mL to > 2.56 mg/mL.

Conclusion: The study concluded that MDR and AO resistance had a similar trend and AO may not be seen as a good antimicrobial agent against MDR strains.